The NFL free agent feeding frenzy begins today — when teams can start negotiating with free agents from other teams but cannot sign them until Friday — and there’s little doubt the Giants will look to add a young, athletic linebacker.

The Giants have often turned to free agency in the past for help at linebacker, with marginal success, and they reportedly have interest in adding Stephen Nicholas this offseason.

It certainly would not be a high-profile signing, but it would be a mid-cost attempt to add depth at a position in need of talent. Nicholas, 28, out of South Florida, spent his first four years with the Falcons, working on special teams the first two seasons and starting 24 games the past two.

Nicholas had a career-high 80 tackles and three sacks in 2009, and tallied 78 tackles in 2010. At 6-foot-3 and 230 pounds, he would also help on special teams.

“We’re excited for Stephen and his family when free agency does hit,” Nicholas’ agent, C.J. LaBoy, told The Post. “We expect there to be a tremendous amount of interest from teams, including the Falcons, who made it very clear before the lockout that they wanted to keep Stephen in Atlanta. Not going to rule anyone out at this point.”

Paul Posluszny of the Bills played for Giants defensive coordinator Perry Fewell in Buffalo and also could attract the attention of the Giants.

There is an opening for a new starting linebacker. Nicholas could be reunited with former Falcons teammate Michael Boley, who is set at one outside spot. Jonathan Goff returns in the middle, and though Goff is not assured of a starting role he was a solid player last season in a limited run-stopping role. The Giants drafted two linebackers: Greg Jones from Michigan State and Jacquian Williams from South Florida. It would be a stretch for either to compete for a starting spot.

Nicholas played on the strong side for the Falcons and word out of Atlanta is he had some issues in coverage. The Falcons decided to tender Nicholas, but he opted not to sign it, though he has said he wants to stay in Atlanta. He also wants a long-term deal, which is why he did not sign the one-year tender.

“I definitely want to come back,” Nicholas said during the lockout, “but why not see what’s out there?”